While many firms have introduced SOA, only one in five have achieved anticipated benefits such as increased IT flexibility or reuse. Industry analysts assume that a lack of SOA governance is the main reason why SOA projects fail. Addressing the substantial research gap on SOA governance this paper theoretically and empirically investigates which SOA governance mechanisms are needed to achieve the benefits of SOA, such as increasing IT flexibility and reusing services. The proposed theoretical SOA governance model is evaluated using data from 81 SOA-using organizations. Overall, the results confirm the relevance of a variety of SOA governance mechanisms (structures, processes, and employees/relations), but at the same time, that IT infrastructure flexibility and service reuse are influenced by different mechanisms. Key governance mechanisms that show a strong effect on infrastructure flexibility are using standards, service management processes, educating employees,  and IT/business communication while reuse can only be increased through service management, standards and qualification. Contrary to expectations, implementing new, dedicated decision-making bodies for SOA hampers organizations in achieving higher degrees of IT flexibility and reuse, and a firm is better off using existing IT decision-making bodies.